Udemy has a good iOS ap which allows me to use it anywhere, even at the gym. Some courses are great and totally worth the time. Others not so: unlike Coursera, anyone can become a Udemy instructor and sometimes courses are not so good as you expect. I took a drawing course from them, and some parts of it weren't that good because the instructor didn't take the time to explain some essentials. Yet, I think anyone can find something to their liking at Udemy, and their prices are irresistible.